A111023 Integers n such that 9*10^n + 11 is a prime number.

1, 2, 3, 4, 6, 8, 16, 20, 27, 115, 180, 274, 576, 1111, 2404, 5127, 8082, 9514, 12808, 14752, 15926, 22670, 37432, 41988, 53707, 72595, 92742

Offset

1,2

Comments

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "90w11".

a(28) > 10^5. - Robert Price, Jan 28 2017

Links

Table of n, a(n) for n=1..27.

Makoto Kamada, List of near-repdigit-related prime numbers.

Index entries for primes involving repunits.

Example

n = 6 is a member because 9*10^6 + 11 = 9*1000000 + 11 = 9000011, which is prime.

Mathematica

Do[If[PrimeQ[9*10^n+11], Print[n]], {n, 1, 1300}] (* Zak Seidov, Sep 14 2006 *)

Crossrefs

Cf. A100275 = numbers n such that 9*10^n-11 is prime.

Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054, A110980.

Sequence in context: A049708 A000031 A298072 * A261751 A294679 A333160

Adjacent sequences: A111020 A111021 A111022 * A111024 A111025 A111026

Keyword

more,nonn

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

Extensions

Edited by N. J. A. Sloane, Apr 11 2008

a(16)-a(22) from Ray Chandler, Dec 23 2010

a(23)-a(27) from Robert Price, Jan 28 2017

Status

approved